This document discusses the design considerations for indoor marijuana grow facilities. It covers advantages of indoor growing like environmental control and year-round harvests. Key factors discussed include lighting options, climate control, odor control, drying and extraction. Power requirements are significant, often requiring a new service. Proper design of grow rooms, ventilation, dehumidification and air circulation are important for plant health and maximum yields.

1. INDOOR MARIJUANA GROW FACILITY DESIGN
Presented by
Bruce Dobbs, P.E.
Mechanical Systems Engineering

2. Advantages of Indoor Growing
• Better Control of
Growing Environment
– Better quality product
– Not at whim of seasons
– Can plant and harvest
throughout the year

3. Indoor Grow Considerations
• Soil or Hydroponics
– Hydroponics produce
larger yields
– Soil growth is easier and
less expensive

4. • Client considerations
– Security & confidentiality
– Lack of construction
experience
– Low budget minded
– Subject to extreme sticker
shock
– Deal in cash
– Extrapolate small scale
grow approaches into large
scale projects
– Inadequate consideration
of utility availability
(especially electric power)

5. • Power Availability
– Have you confirmed that
power is available?
– What voltage/phase is
available?
– Will your budget allow
for new power service if
utility does not have
adequate capacity?
– Is CHP and option?
• Typical Power
Requirement for 10,000
sf facility
– Lights 160 kW
– AC/Dehumidifier 77 kW
– Electric Heat 10 kW
– Recirculation Fans 20 kW
– Exhaust Fans 5 kW
– Miscellaneous 20 kW
– Total: 787 kW

6. • Client Considerations
– Minimal Architectural &
Civil Design

7. Grow Room Layout

8. Design Considerations
• Odor control
• Temperature & humidity
control
• THC resin adhesion to
surfaces
• Utility availability
– Electricity
– Gas
– Water
• Client budget
• Annual energy costs

9. Types of Lighting
• Three Main Types of
Lighting
– Compact Fluorescent Lights
– Light Emitting Diode (LED)
– High Intensity Discharge (HID)

10. Cannabis Lighting
• Lumens & Kelvin
– Lumens measure brightness
of light
– Kelvin measures color
temperature emitted by bulb

11. Cannabis Lighting
• LED Lighting
– Low heat production
– Reduced A/C Load
– 60,000 hour life
– Slow early adoption

12. Flowering & Light Cycles
• Flowering Marijuana
– Female plant starts to
produce buds
• When is Plant Ready for
Flowering
– Cannabis doesn’t flower
because of size or age
– Flowers as function of light
cycles

13. Flowering & Light Cycles
• Vegetative growth of 4 – 5
weeks is recommended
• Bring plant to flower when
½ the size you want it to be
during flowering
– Plant will grow to 2 to 2 ½
times it’s vegetative size

14. Flowering & Light Cycle
• Flowering Timeline
– Varies by strain
• Rough Guidelines
– 1 to 2 Weeks: 1st flowers start to
show after switching to 12/12 light
cycle
– 3 to 5 Weeks: Plants stretch for light
and flowers appear at nodes
– 5+ Weeks: Buds start to thicken.
Flowers close. Leaves will yellow as
energy used to make flowers. Plant
reaches its flowering peak
– Final 2 Weeks: Flush the plants using
clean water
– Final 48 Hours: Further flush
nutrients and unwanted sugars by
turning out all light

15. Flowering & Light Cycle
• Types of Flower
– Female
• Main aim for growers
– Sensimilla
• Marijuana flowering that has not
been pollinated
• Most potent (most THC)
• Most prized of plants
– Male
• Doesn’t produce buds for smoking
• Produce pollen used for seed
production
– Hermaphrodite
• Created thru stress during early
flowering. Lacks potency of
Sensimilla.

16. Flowering & Light Cycle
• Lighting Cycle
– Mimic Fall/Winter Lighting
Conditions
• Vegetative Growth Stage
– 18/6 hour cycle
• Flowering Stage
– 12/12 hour cycle
– Reduce number of lumens
• Change from 6500k to 2700k
– Marijuana a fall flowering plant
so we’re reproducing fall
lighting conditions

17. Indoor Climate Considerations
• Photosynthesis
• Evapotranspiration
• Lighting Loads
• Irrigation Methods
• Properly Directed Air
Movement
– Beneficial vapor differentials
– Improved transpiration rates
• Changing SHF
– Vary depending on plant
growth & levels of vegetation
and whether lights on or off

18. Clackamas County Code

19. Marijuana Odor Control
• Strong odor production
must be controlled
• Carbon Filtration
– Recirculated air
• Filtration Rate = (Room Volume)/3
– Exhaust air
• Filtrate air being exhausted from space
• Ozone Generator
– Neutralizes odor by oxidizing bad smells
with ozone
– Extra Oxygen molecule attaches to
contaminants and O3 turns to O2,
creating safer work environment

20. • Photosynthesis
– When exposed to light, plant
converts CO2 and water into
food
• Transpiration
– Plant uses water to carry
nutrients throughout their
tissues then release water as
water vapor via stomata to
surrounding boundary layer
air
Transpiration Through Stomata

21. • Vapor Pressure Differential
– Drives respiration
– Temperature of leaves affects
transpiration
– Internal plant temperature
regulated by water
evaporating within the plant
– VPD must be properly
controlled to avoid heat
stress to plant

22. • Latent load Determination
– Option 1: Equals the
difference in the amount of
water added through
irrigation and the amount of
water that goes to drain
– Option 2: Calculate using
Penman-Monteith Formula
– Option 3: Use industry
averages
• 0.25 to 0.50 gal/plant/day
• 2 sf/plant Penman-Monteith Formula

23. • Penman Monteith Formula
– Used to calculate TR
John Monteith Howard Penman

24. Air Cooled Lighting

25. • Modulating Sensible Heat
Ratios
– Plant moisture release changes
as they grow
• Evapotransrespiration higher
as plants grow
– Lighting loads vary depending
on whether on or off
– Problems occur when lights
turned off before moisture
(latent heat) has been
absorbed
• Thermostat satisfied and unit
goes off before removing
latent load

26. Dehumidifier Schematic

27. • Dehumidifier Selection
– Quantities/Types of lights
– Heat loss when lights off
– Type of watering system
– Amount of water
evaporated/transpired
– Grow room volume
– Optimal air circulation
– Temp/RH in each grow phase

28. Air Circulation
• Air Circulation
– Cannabis plant uses
substantial amount of
CO2
– Laminar flow air
movement minimizes
stress on plant
– Recirculate air for odor
control

29. Marijuana Drying
• Ideal Environmental
Conditions
– Temperature: 65F to 75F
– Humidity: 45% to 55%
• Drying period is 5 to 9 days
• Maintain slow air velocities
– High velocities dry the
product too quickly (causes
bad tasting cannabis)

30. Proving Grounds
• 22 grow rooms
– (8) 1000 watt HID lights
– 30,000 Btuh cooling load
– Design Conditions: 75F/50% RH
• Drying room
– Design Conditions: 75F/50% RH

31. Proving Grounds Floor Plan

33. Proving Grounds Details and Elevations

34. Air Cooled Lighting

35. Extraction Facilities
• Extraction oils
significantly more
potent than buds
• Usually used for
medical marijuana
• Extraction of pure THC
• Methods
– CO2
– Butane (Volatile)
Butane Extraction Process

36. Extraction Facilities
• Design considerations
– Dedicated exhaust and
makeup air serving
extraction room
– Extraction room 1-hour
rated
– Exhaust fan to be Class 1
Div 2 rated.
– All electrical equipment
within 10’ of extraction
equipment to be Class 1
Div 2
– Charcoal filtered exhaust
and return air CO2 Extraction System

37. CO2 Extraction Facility